Chelating agents are used in biochemistry to remove or inactivate divalent cations that can lead to deleterious and unwanted effects in the reaction. The current use of EDTA as a chelator in sequencing related sample preparation applications can lead to severe and irreversible oxidation of the DNA especially in the presence of contaminating iron, due to the generation of an Fe2+(EDTA) complex which promotes damaging free-radical chemistry (Lloyd and Phillips, Mutation Res. (1999) 424:23-36; Wang et al., Nuc. Acid Res. (2008) 36:e85). This results in local point mutations in the DNA sample leading to erroneous polymorphism calls during deep sequencing analysis. This phenotype is especially problematic in cancer-related deep sequencing applications where low frequency polymorphisms must be detected sensitively and are of great biological significance.